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3 years ago

I need simple answers that a 14-year-old would understand.

Chemistry

1 answer:

Nana76 [90]3 years ago

4 0

Answer:

1. The Nummber of electrons present in the outermost shell is called Valence electrons.

2. Thomson model:

Thomson model of atom is the model which states that electrons are embedded in a positively charged solid material which is spherical in shape.

Rutherford model

Rutherford model of atom is the model which explains that there is a nucleus in the center of the atom and electrons are located around the nucleus.

3. Relative atomic mass. Atoms have very little mass , so they're difficult to measure accurately. Instead, chemists use a scale. On this scale the mass of a 12C atom is exactly 12.

4. Difference between Alpha, Beta and Gamma radioactive decay:

Alpha decay forms new element with two fewer protons and two fewer neutrons;

Beta decay forms new element with one more proton and one fewer neutron.

Gamma decay forms NO new element, but now the element has less energy because energy is released as gamma rays.

Gamma radiation has the highest penetration power, Beta decay goes the second, alpha decay the last. However, alpha particles make the most damage even if it has the lowest penetration power among the three.

5. This species has a 2− charge on it, so it is an anion. Anions are named using the stem of the element name with the suffix -ide added. This is the oxide anion.

Hope it helps....Pls Mark as Brainliest!! I Have answered all your question in the Simplest way i could...

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ivolga24 [154]

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3 years ago

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What must be the molarity of an aqueous solution of trimethylamine, (ch3)3n, if it has a ph = 11.20? (ch3)3n+h2o⇌(ch3)3nh++oh−kb

Stolb23 [73]

0.040 mol / dm³. (2 sig. fig.)

<h3>Explanation</h3>

$(\text{CH}_3)_3\text{N}$ in this question acts as a weak base. As seen in the equation in the question, $(\text{CH}_3)_3\text{N}$ produces $\text{OH}^{-}$ rather than $\text{H}^{+}$ when it dissolves in water. The concentration of $\text{OH}^{-}$ will likely be more useful than that of $\text{H}^{+}$ for the calculations here.

Finding the value of $[\text{OH}^{-}]$ from pH:

Assume that $\text{pK}_w = 14$ ,

$\begin{array}{ll}\text{pOH} = \text{pK}_w - \text{pH} \\ \phantom{\text{pOH}} = 14 - 11.20 &\text{True only under room temperature where }\text{pK}_w = 14 \\\phantom{\text{pOH}}= 2.80\end{array}$ .

$[\text{OH}^{-}] =10^{-\text{pOH}} =10^{-2.80} = 1.59\;\text{mol}\cdot\text{dm}^{-3}$ .

Solve for $[(\text{CH}_3)_3\text{N}]_\text{initial}$ :

$\dfrac{[\text{OH}^{-}]_\text{equilibrium}\cdot[(\text{CH}_3)_3\text{NH}^{+}]_\text{equilibrium}}{[(\text{CH}_3)_3\text{N}]_\text{equilibrium}} = \text{K}_b = 1.58\times 10^{-3}$

Note that water isn't part of this expression.

The value of Kb is quite small. The change in $(\text{CH}_3)_3\text{N}$ is nearly negligible once it dissolves. In other words,

$[(\text{CH}_3)_3\text{N}]_\text{initial} = [(\text{CH}_3)_3\text{N}]_\text{final}$ .

Also, for each mole of $\text{OH}^{-}$ produced, one mole of $(\text{CH}_3)_3\text{NH}^{+}$ was also produced. The solution started with a small amount of either species. As a result,

$[(\text{CH}_3)_3\text{NH}^{+}] = [\text{OH}^{-}] = 10^{-2.80} = 1.58\times 10^{-3}\;\text{mol}\cdot\text{dm}^{-3}$ .

$\dfrac{[\text{OH}^{-}]_\text{equilibrium}\cdot[(\text{CH}_3)_3\text{NH}^{+}]_\text{equilibrium}}{[(\text{CH}_3)_3\text{N}]_\textbf{initial}} = \text{K}_b = 1.58\times 10^{-3}$ ,

$[(\text{CH}_3)_3\text{N}]_\textbf{initial} =\dfrac{[\text{OH}^{-}]_\text{equilibrium}\cdot[(\text{CH}_3)_3\text{NH}^{+}]_\text{equilibrium}}{\text{K}_b}$ ,

$[(\text{CH}_3)_3\text{N}]_\text{initial} =\dfrac{(1.58\times10^{-3})^{2}}{6.3\times10^{-5}} = 0.040\;\text{mol}\cdot\text{dm}^{-3}$ .

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Societal and economical

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During the process of heat transfer, the heat transferred to or from a system's surroundings is always?

OleMash [197]

Answer:

During the process of heat transfer, the heat transferred to or from a system's surroundings is always equal in magnitude to the heat transferred to or from the system, but opposite in sign.

<h2>What is the 1st law of thermodynamics?</h2>

The total energy of an isolated system is said to stay constant according to the first rule of thermodynamics. Energy cannot be generated or destroyed, but it may be transformed from one form into another inside a closed system, which is known as the conservation of energy.

This rule states that when a system is exposed to a certain amount of heat, the amount of heat that the system absorbs is equal to the product of the increase in internal energy (change in internal energy) of the system and the external work that the system does. The relationship between a system's internal energy and work output and the heat given to it is demonstrated by the first law of thermodynamics. This equation provides the foundation for the majority of practical innovations like heat engines, freezers, and air conditioners.

The equation for the first law of thermodynamics is given as; ΔU = q + W

Where,

ΔU = change in internal energy of the system.
q = algebraic sum of heat transfer between system and surroundings.

W = work interaction of the system with its surroundings.

The heat transported to or from a system's surroundings during the process of heat transfer is always opposite in sign, but equal in size, to the heat transferred to or from the system.

What is heat transfer?

The flow of thermal energy between physical systems is known as heat transfer. The temperatures of the systems and the characteristics of the medium used to transmit the heat affect how quickly it transfers. Conduction, convection, and radiation are the three basic ways that heat is transferred. It is crucial to employ heat transfer, or the movement of energy in the form of heat, in applications of the First Law of Thermodynamics since it is a mechanism through which a system changes its internal energy. Diffusion and conduction are two different concepts. Diffusion linked to fluid mixing is not the same as conduction.

The Second Law of Thermodynamics controls the direction of heat transmission, which is from one area of high temperature to another area of lower temperature. The internal energy of the systems from and to which the energy is transmitted is altered during heat transfer. Heat transfer will take place in a way that makes the group of systems' entropy higher.

In physics, heat is described as the flow of thermal energy over a boundary that is clearly defined surrounding a thermodynamic system. The amount of work that a thermodynamic system may accomplish is known as the thermodynamic free energy. Enthalpy is a thermodynamic potential with the letter "H" that is made up of the system's internal energy (U) plus the volumetric product of pressure (P) and temperature (T) (V). A joule is a unit used to measure energy, effort, or heat production.

The quantity of heat transmitted in a thermodynamic process that modifies a system's state relies on how that process happens, not just the net difference between the process' beginning and ending states, since heat transfer is a process function (or route function), as opposed to a function of state.

The heat transfer coefficient, which represents the relationship between the heat flux and the thermodynamic force that drives the flow of heat, is used to determine both thermodynamic and mechanical heat transfer. A quantitative, vectorial description of the movement of heat through a surface is called a heat flux.

The term "heat" is sometimes used interchangeably with "thermal energy" in technical applications. This usage derives from the historical understanding of heat as a fluid (caloric) that may be transported by a variety of reasons, which is also prevalent in laypeople's language and daily life.

Thank you,

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1 year ago

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